As a woman who is able to orgasm from PIV, 5min would not be nearly long enough to get me to a point where any amt of PIV would get me off. I’d suggest looking into more ‘foreplay’ techniques and make that more of a focus. It boggles my mind how people jump straight to PIV, like that IS sex; MANY things feel as good, if not better than PIV and can be equally as enjoyable for the male partner, if mutual pleasure is the goal and there isn’t a race to the finish. If your partner truly truly wants PIV, maybe invest in a quality dildo you can use on her until she’s close and your ready to finish. There’s also no rule that you have to finish together if you’re both getting what you need. There’s no reason you should feel the ‘need’ to last longer if the time spent together is focused on pleasure since there are so many other ways to do it. I understand this may also take a mindset shift with your partner and being open to exploring other avenues of pleasure so your closer to the same point when your ready to designate your time to PIV.